Onion-like carbon based single-atom iron nanozyme for photothermal and catalytic synergistic antibacterial application

Nanozymes with oxidase (OXD)-like activity have emerged as promising antibacterial agents due to their capability of catalyzing atmospheric O2 to generate highly active free radicals. However, the precise engineering of functional nanozyme at the atomic level for antibacterial therapy presents a challenge. Here, atomically dispersed Fe atoms were loaded onto onion-like carbon (OLC) through a ligand-assisted calcination strategy, yielding a single-atom nanozyme (FeSA-OLC) with enhanced oxidase-like activity. The FeSA-OLC could catalyze the decomposition of O2 to produce active hydroxyl radicals (& sdot;OH) owing to the fully exposed Fe atoms and a highly curved carbon shell. Density functional theory calculation revealed that the single-atom Fe sites facilitated the generation of free radical species by promoting the adsorption and cleavage of O-O bond. Meanwhile, the FeSA-OLC exhibited a notable photothermal conversion efficiency of 66.48% under near-infrared laser irradiation. Furthermore, in vitro experimental results demonstrated a synergistic antibacterial effect towards Escherichia coli due to the photothermal-enhanced oxidase-like activity. Overall, this work introduced a strategy to develop OLC-based single-atom nanozyme, thereby offering new avenues for photothermal-augmented antibacterial therapy.